68 lines
2.3 KiB
C++
68 lines
2.3 KiB
C++
// mapnik
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#include <mapnik/feature_factory.hpp>
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#include <mapnik/geometry.hpp>
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#include "hello_featureset.hpp"
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hello_featureset::hello_featureset(mapnik::box2d<double> const& box, std::string const& encoding)
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: box_(box),
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feature_id_(1),
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tr_(new mapnik::transcoder(encoding)),
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ctx_(boost::make_shared<mapnik::context_type>()) { }
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hello_featureset::~hello_featureset() { }
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mapnik::feature_ptr hello_featureset::next()
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{
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if (feature_id_ == 1)
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{
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// let us pretend it just has one column/attribute name
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std::string attribute("key");
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// the featureset context needs to know the field schema
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ctx_->push(attribute);
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// create a new feature
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mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx_,feature_id_));
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// increment the count so that we only return one feature
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++feature_id_;
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// create an attribute pair of key:value
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UnicodeString ustr = tr_->transcode("hello world!");
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feature->put(attribute,ustr);
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// we need a geometry to display so just for fun here
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// we take the center of the bbox that was used to query
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// since we don't actually have any data to pull from...
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mapnik::coord2d center = box_.center();
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// create a new point geometry
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mapnik::geometry_type * pt = new mapnik::geometry_type(mapnik::Point);
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// we use path type geometries in Mapnik to fit nicely with AGG and Cairo
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// here we stick an x,y pair into the geometry using move_to()
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pt->move_to(center.x,center.y);
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// add the geometry to the feature
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feature->add_geometry(pt);
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// A feature usually will have just one geometry of a given type
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// but mapnik does support many geometries per feature of any type
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// so here we draw a line around the point
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mapnik::geometry_type * line = new mapnik::geometry_type(mapnik::LineString);
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line->move_to(box_.minx(),box_.miny());
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line->line_to(box_.minx(),box_.maxy());
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line->line_to(box_.maxx(),box_.maxy());
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line->line_to(box_.maxx(),box_.miny());
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line->line_to(box_.minx(),box_.miny());
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feature->add_geometry(line);
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// return the feature!
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return feature;
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}
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// otherwise return an empty feature
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return mapnik::feature_ptr();
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}
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